Chrysler neon 1997 Service Manual page 1319

14 - 32 FUEL SYSTEM
DESCRIPTION AND OPERATION (Continued)
SCI RECEIVE—PCM INPUT
SCI Receive is the serial data communication
receive circuit for the DRB scan tool. The Powertrain
Control Module (PCM) receives data from the DRB
through the SCI Receive circuit.
PARK/NEUTRAL POSITION SWITCH—PCM INPUT
The park/neutral position switch is located on the
automatic transaxle housing (Fig. 17). Manual tran-
saxles do not use park/neutral switches. The switch
provides an input to the PCM to indicate whether
the automatic transaxle is in Park/Neutral, or a drive
gear selection. This input is used to determine idle
speed (varying with gear selection) and ignition tim-
ing advance. The park/neutral input is also used to
cancel vehicle speed control. The park/neutral switch
is sometimes referred to as the neutral safety switch.
Fig. 17 Park/Neutral Switch
THROTTLE POSITION SENSOR—PCM INPUT
The throttle position sensor mounts to the side of
the throttle body (Fig. 18) and (Fig. 19).
The Throttle Position Sensor (TPS) connects to the
throttle blade shaft. The TPS is a variable resistor
that provides the PCM with an input signal (voltage).
The signal represents throttle blade position. As the
position of the throttle blade changes, the resistance
of the TPS changes.
The PCM supplies approximately 5 volts DC to the
TPS. The TPS output voltage (input signal to the
powertrain control module) represents throttle blade
position. The TPS output voltage to the PCM varies
from approximately 0.35 to 1.03 volts at minimum
throttle opening (idle) to a maximum of 3.1 to 4.0
volts at wide open throttle.
PARK/NEUTRAL TRANSAXLE HOUSING SWITCH
THROTTLE POSITION SEN- IDLE AIR CONTROL Along with inputs from other sensors, the PCM IDLE CONTROL MOTOR THROTTLE SHIELD
uses the TPS input to determine current engine oper-
ating conditions. The PCM also adjusts fuel injector
pulse width and ignition timing based on these
inputs.
Fig. 18 Throttle Position Sensor and Idle Air Control
Fig. 19 Throttle Position Sensor and Idle Air Control
MOTOR PURGE HOSE SOR POSITION SEN- THROTTLE
Motor—SOHC
Motor—DOHC
PL
SOR